Windows7 still have a memory leak in audiodg.exe. Unfortunately I have discovered 4 month and a 4GB memory expansion late. You can solve it restarting Windows Audio service from time to time.
I am a linux person but my computer was too new for linux so I ended with Windows 7 professional (even for windows I needed to install a lot of samsung's drivers and still are things that does not work properly). I usually does not shut down my laptop for months (suspend to ram works OK). But with this computer I needed to restart it once a week. When it had only 4GB it was getting quickly out of memory and windows, in its big desire to be helpful in its own ways, was closing programs at will with a polite notice ('sorry your computer has low memory I am going to close some programs') but without actually allowing you to decide. I bought another 4GB memory card, and then it takes 10 days before reaching to 31GB of virtual memory plus the 8GB of real memory and start to complain.
I thought that this was due to my abuse of firefox tabs (usually 150-200 opened tabs) and the cache problem, plus a lot of other programs in use like thunderbird, a linux virtual machine with 2GB, word, Xmind, excel, R....
I have seen several times one process with a lot of memory but always left aside (audiodg.exe). Finally today with all 31GB virtual memory full and some windows warnings, closed firefox and chrome and I did not see any relevant change in the memory consumed, still 29GB after 1 hour. Looking at the Processes I saw that audiodg.exe had 25GB virtual memory allocated and 2GB real memory in use!!!!
A quick google search shows that since 2009 is well known that audiodg.exe has a memory leak and there is a hot-fix for it (unfortunately people say that it does not work with windows 7). Some folks solved the problem restarting the audio server. I went to adminitrative_tools/componet_services and searched for audiodg. It was not there but there was a windows audio service. I restarted it and then the real memory used went from 8 to 3GB and the virtual memory from 29 to 4GB!!!!!!!!!!!
My computers just after restarting Windows Audio